Digest for sci.electronics.repair@googlegroups.com - 18 updates in 7 topics

Amanda Ripanykhazov <dmanzaluni@gmail.com>: Sep 24 07:32AM -0700

Is there some overwhelming technical problem with replacing a Priv screen please?
 
All screen replacement services are MASSIVELY expensive (the LCD alone seems to cost $180) and places like ebay are full of Privs on which the owners seemingly cant replace their cracked screens?
 
Curiously, ebay sales are rife with digitiser offers, - where the digitiser cant actually be replaced because it cant practically be separated from the LCD! What is going on?? On every other cellphone the repair cost nose-dives when the phone stops being current!
Stephen Wolstenholme <steve@easynn.com>: Sep 24 04:04PM +0100

On Sun, 24 Sep 2017 07:32:38 -0700 (PDT), Amanda Ripanykhazov
 
>Is there some overwhelming technical problem with replacing a Priv screen please?
 
>All screen replacement services are MASSIVELY expensive (the LCD alone seems to cost $180) and places like ebay are full of Privs on which the owners seemingly cant replace their cracked screens?
 
>Curiously, ebay sales are rife with digitiser offers, - where the digitiser cant actually be replaced because it cant practically be separated from the LCD! What is going on?? On every other cellphone the repair cost nose-dives when the phone stops being current!
 
Watch https://www.youtube.com/watch?v=lRj_F7b4JvE
 
It looks a bit tricky with my jumbo fingers!
 
--
http://www.npsnn.com
Amanda Ripanykhazov <dmanzaluni@gmail.com>: Sep 24 08:54AM -0700

Thank you for that but this makes the question even more baffling!
The screen-only repair is not difficult, in fact not only is it easy, it is a 5-10 minute job!
 
why on earth is it so expensive? I can't believe that this screen is made by any different company from galaxy/iphone/etc screens?
Jeff Liebermann <jeffl@cruzio.com>: Sep 23 09:52AM -0700

>> necessary.
 
>Oh, you've found a zener that's 10v +/- 1%?
>NT
 
The meter isn't even that accurate. You're not going to be able to
read the meter to +/- 0.1V. Also, I coulnd't find where anyone
specified the accuracy required.
 
If you really want 1% accuracy, maybe a 10.0V precision reference,
such as the TI REF102:
<http://www.ti.com/lit/ds/symlink/ref102.pdf>
However, there's a problem. The IC requires a V+ of 11.4-36VDC which
will probably require a battery or other power supply.
 
Hmmm... I sorta blundered across this idea:
<http://www.qsl.net/kh6grt/page4/expscale/expscale.htm>
It doesn't expand the entire meter scale from 10-15VDC.
Instead, it compresses 0-10V into a small part of the meter scale, and
expands the 10-15V over the rest of the scale. However, it requires
+12v and -12v power.
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
tabbypurr@gmail.com: Sep 23 10:46AM -0700

On Saturday, 23 September 2017 17:35:36 UTC+1, Jeff Liebermann wrote:
 
> >fails to solve the issue AND adds pointless cost.
> >NT
 
> The consensus seems to be to use an expanded scale analog voltmeter.
 
that's part of the spec
 
> If the OP is going to build such a thing, he needs a new scale on his
> analog meter.
 
yes
 
> That can be done with the free version of the software.
> (I just checked and it will do an expanded scale).
 
it can
 
> I usually ignore one line pontifications, but I'm curious. Why does a
> new meter scale fail to solve the issue? Ummm... what issue?
 
The issue with using an inaccurate zener is that the meter scale most likely won't run from 10.0v, and will thus need calibrating over its scale. That also means a new scale with marks in new places - a pita to do. Far easier to knock off 10v exactly then just change the numbers on the scale.
 
 
NT
tabbypurr@gmail.com: Sep 23 10:58AM -0700

On Saturday, 23 September 2017 17:52:35 UTC+1, Jeff Liebermann wrote:
 
> >Oh, you've found a zener that's 10v +/- 1%?
> >NT
 
> The meter isn't even that accurate.
 
We don't know the meter's accuracy. 1% is common enough, but it might be worse. (For all we know it might even be a moving iron thing.)
 
> You're not going to be able to
> read the meter to +/- 0.1V.
 
Even my most rock bottom multimeters, under $3 each new, are easy to read to 1%. Decent meters do much better.
 
> Instead, it compresses 0-10V into a small part of the meter scale, and
> expands the 10-15V over the rest of the scale. However, it requires
> +12v and -12v power.
 
Nice idea, though I don't expect the op needs it. I'm sure one could design a circuit that can use opamps that are happy on the 10-15v and halve V_in.
 
 
NT
mike <ham789@netzero.net>: Sep 24 04:05AM -0700

On 9/22/2017 1:29 AM, T i m wrote:
> the question. I left it open to the reader to ask any supplementary
> questions as they felt relevant. ;-)
 
> Cheers, T i m
 
Metrology is an interesting topic.
 
When someone asks me how to measure something, my first thought is,
"exactly how will the answer to your question improve YOUR life tomorrow?"
Sometimes I actually say it.
The "jolt" to their thought process forces them to express what they're
trying to accomplish...or admit to themselves that they have no idea.
I find that almost all questions end up in the "won't affect them at all"
category and I can dispense with trying to teach them something they'll
never use. If the answer won't change the future, don't bother with the
question.
 
It's similar to pointless social interaction.
People you don't know ask questions, like "how are you?"
They think they know what you'll say.
Respond with something like, "I have this rash on my dick and
think I need to find a different street corner... got any ideas?"
to see how much they really care about how you are. ;-)
But I digress...
 
If I had an electric boat, the ability to measure voltage to six
decimal places would not be my priority.
What I want to know is, "can I get back to the dock?"
You can do that more accurately with a sharpie and nonlinear
meter than you can react to a change in wind direction.
 
The river current and wind and the shape of the curve of distance covered vs
velocity and temperature would be far more important variables to me.
Amp hours consumed would be important.
 
Battery voltage that would be strongly impacted by whether I'm going
up or down stream at what net velocity is a poor substitute.
 
An integrating current meter, a water speed speedometer and a GPS would
much more interesting. If you knew the water flow direction and speed,
you probably wouldn't have to measure anything else other than
what you can get from the GPS. Drifting downstream for a minute
would give you those two numbers.
 
But, since you're dead set on measuring voltage...
The basic problem is that the voltage you want to measure is
the biggest voltage you have to power your circuit.
That's why I split my original post into the concept (battery)
and the implementation (zener).
A series zener needs to draw ZERO current at 10V and still
be 10V at MUCH higher current ratio. You will have to live
with some amount of nonlinearity.
 
You could stack an AA-cell or two on top of your battery system
and alleviate that problem.
 
I maintain that a digital voltmeter is the best option.
They're dirt cheap on EBAY.
 
All the above is based on an extreme extrapolation of
very limited information. That's why the system spec is so important.
tabbypurr@gmail.com: Sep 24 06:31AM -0700

On Sunday, 24 September 2017 12:06:45 UTC+1, mike wrote:
 
> A series zener needs to draw ZERO current at 10V and still
> be 10V at MUCH higher current ratio. You will have to live
> with some amount of nonlinearity.
 
In fact you could re-zero the meter so it reads 10v spot on. Add an extra mark for where it points when unpowered so you can see if it ever decalibrates.
 
 
> You could stack an AA-cell or two on top of your battery system
> and alleviate that problem.
 
yuck. 2 resistors beats 2 cells any day.
 
> I maintain that a digital voltmeter is the best option.
> They're dirt cheap on EBAY.
 
but noncompliant with the basic spec
 
 
NT
micky <NONONOmisc07@bigfoot.com>: Sep 23 10:59PM -0400

People on Amazon ask some of the stupidest questions (he said, as he's
about to ask one).
 
I"m looking at a panel-mount extension cord for a car radio with USB and
3.5mm inputs, and someone asks "could i use this to connect a usb
headset to the 3.5mm headphone jack on my tv?"
 
And all the answers related to the fact that it uses two unconnected
cables, and about converting from one jack to another, and I thought the
problem was deeper than that, that there is no way to make an adapter
from the audio output of a 3.5mm jack to a USB headset, because, well,
it's USB! It's uses some sort of fancy USB signal, like all the other
USB devices do. It doesn't have L+, R+ and ground, like earphones with
round plugs on the end have. OR does it?
 
BTW, I use little powered Logitech USB speakers with my laptop and they
get their power from the USB, and they work very well. If I'm wrong
above, does the power piggyback on one of the 3 wires or does it use the
fourth wire?
 
Tnx.
"~misfit~" <shaun.at.pukekohe@gmail.com>: Sep 25 02:15AM +1300

Once upon a time on usenet micky wrote:
> they get their power from the USB, and they work very well. If I'm
> wrong above, does the power piggyback on one of the 3 wires or does
> it use the fourth wire?
 
Maybe the 5th - the shield ground?
--
Shaun.
 
"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)
"~misfit~" <shaun.at.pukekohe@gmail.com>: Sep 25 02:11AM +1300

Once upon a time on usenet Percival P. Cassidy wrote:
> will depend on how densely it's packed -- could be as little as 5 oz.
> rather than the 8 oz. that the "pint's a pound the world around"
> formula indicates.
 
At school I was taught 'A pint of water weighs a pound-and-a-quarter'. Then
again that was in England.
--
Shaun.
 
"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)
Paul in Houston TX <Paul@Houston.Texas>: Sep 23 12:30PM -0500

micky wrote:
> the car speakers and an add-on microphone (in addition to the first
> $150).
 
> The most important feature for me is the USB input.
 
Forget the input jack and use FM wireless. Search Ebay.
 
IMO, bluetooth phone in a vehicle does not work very well.
The outgoing sounds are muffled, distorted, and hard to understand.
However, if you want to send music from your ipod to the vehicle
audio it works well enough.
micky <NONONOmisc07@bigfoot.com>: Sep 23 09:00PM -0400

In rec.autos.tech, on Sat, 23 Sep 2017 11:01:57 -0400, micky
 
>There are one or two other companies that sell devices that have
>everything but the USB input, and I found something on ebay that had
>everything and was only $18.
 
Correction: It only has USB and AUX. When I came across it, totally by
chance, I didn't think I could add on even that much. I thought I'd
have to buy a newer radio, and I certainly hadn't considered Bluetooth.
 
 
>case it works, but based on the pictures, I don't think I could find one
>that fit my particular jack. Hmm. Now it says "Only 4 available" and
>the price has gone up to $20.
 
Correction, now for this particular car, it says 0 available but good
news, the price is down to $18.
 
 
If you want to look for more, the search terms are car kit .
I find that amazing considering there must be kits for all sorts of
things, but apparently they don't get to use the term car kit.
 
Crutchfield has 13 things, not all with good reviews:
https://www.crutchfield.com/S-gdyc2ktbWNt/g_324750/Bluetooth-Car-Adapters-Hands-free-Kits.html
I can't find the one I looked at before, unless it was the one for 89
dollars
 
but there are loads of other by lots of companies running from $40 to
270. the last one includes HD radio, but for that you have to mount an
antenna a little smaller than a bic lighter inside the windshield or so.
micky <NONONOmisc07@bigfoot.com>: Sep 23 10:50PM -0400

In rec.autos.tech, on Sat, 23 Sep 2017 12:30:27 -0500, Paul in Houston
>> $150).
 
>> The most important feature for me is the USB input.
 
>Forget the input jack and use FM wireless. Search Ebay.
 
Do you mean something like this:
 
http://www.ebay.com/itm/Wireless-Music-to-Car-Radio-FM-Transmitter-For-3-5mm-MP3-iPod-iPhone-Tablets-US-/172506628087?hash=item282a323ff7:g:6qoAAOSwImRYjlrj
 
Or this one is ridiculously cheap
http://www.ebay.com/itm/like/381848425256?chn=ps&dispItem=1 ? this
uses a 3.5mm input from a cell phone, but I don't think I'll be using a
cell phone. I can't afford unlimited data. Most likely I'll be dl'ing
podcasts and putting them on a flashdrive. Although I have to say it
might be worth buying this anyhow. It's only $2.85 with free shipping!
OT3H I found a half dozen seller who'd sold over 1000 and only 1 review
came back! He said it broke after a month. ;-)
 
How can cellphone makers consider getting rid of the 3.5mm jack with so
many things that use it?
>The outgoing sounds are muffled, distorted, and hard to understand.
>However, if you want to send music from your ipod to the vehicle
>audio it works well enough.
 
Actually, the radio itself has plenty of music and I just want to send
talk, downloaded podcasts. That requires even less quality, iiuc.
Paul in Houston TX <Paul@Houston.Texas>: Sep 23 11:37PM -0500

micky wrote:
> might be worth buying this anyhow. It's only $2.85 with free shipping!
> OT3H I found a half dozen seller who'd sold over 1000 and only 1 review
> came back! He said it broke after a month. ;-)
 
What is a "flashdrive"?
If it is a usb stick then there are devices to play usb music with fm.
My son had one in his last car but I don't know which brand.
It worked pretty good.
 
http://www.ebay.com/itm/Bluetooth-Wireless-Car-Aux-Stereo-Usb-Charger-Audio-Receiver-Fm-Radio-Sd-Adapter/382234256138?_trkparms=aid=222007&algo=SIM.MBE&ao=2&asc=47507&meid=48182c1016f24b978496634f4e4d0ba8&pid=100623&rk=2&rkt=6&sd=192247227744&_trksid=p2047675.c100623.m-1
 
http://www.ebay.com/itm/Bluetooth-Wireless-Car-AUX-Stereo-Audio-Receiver-FM-Radio-Adapter-USB-Charger-SD-/192247227744?epid=21003076227&hash=item2cc2d3e560:g:TeIAAOSw~e5ZQEdu
Bruce Esquibel <bje@ripco.com>: Sep 24 10:29AM


> Do any of you know anything good or bad about Grom audio? Do any of you
> know a competitor you would recommend (instead?)?
 
No comment on them but a general 2-cent comment.
 
Keep in mind that most of these "adapters" need power, usually by a
rechargeable battery built into them and that is the major pain in the ass.
 
I had a 97 Lincoln that had a non-replaceable radio (amps and other parts of
it were scattered all over the car), it had a cassette player and 10 disc cd
changer but since you can get like 1400 mp3's on a cheap 16GB ipod, I wanted
to use one of those.
 
They probably are still made (maybe) but there was a cassette to bluetooth
adapter and it really worked well, provided it was charged up. Battery life
was only 4-6 hours and it really sucked when 15 minutes into a 2 hour drive
it starts beeping at you to charge it up. Back to the radio.
 
I'd really recommend if whatever you are looking at isn't wired into the
car, forget it.
 
My overall recommendation is screw all these adapters and replace the radio.
 
I don't know what kind of car or truck you have but you should be able to
find from Crutchfield, a radio, wiring harness that supports the steering
wheel controls and if needed, the adapter plate (bezel) for $150 or less.
 
Most of those under $100 radios they sell have at least 1 usb port (the dual
ones are front/back, the back if you want to run a cable somewhere), usually
bluetooth and have a aux input.
 
My point is, it's a little more expensive than it seems you are planning on,
will take at least an afternoon of work to install but once it's done, you
just don't have to worry about anything. Provided you remember to bring the
phone/ipod or usb stick with you, it just works.
 
I put up with that cassette adapter for 4-5 years and although it was worth
the $35 or so it just wasn't dependable. I replaced the car earlier this
year with another used Lincoln, but the at least the radio was more
standard. I wanted to try that apple carplay and although it ran almost $500
for everything, I'd never get another car without it.
 
I'm pushing 60 and the last car radio I installed was back when dashboards
were still made of steel and although it took me 3 attempts over 3 days to
get everything to work right (who would of thunk to attach the tripwire for
the amps to the power antenna lead from the radio), I'd do it again in a
heartbeat.
 
I stuffed all the wiring via the shift tunnel into the center console thing
and don't have any wires or plugs exposed. If you go on a short trip and
don't plug the phone/ipod in, the radio does a search for a bluetooth
connection automatically and off ya go. Can still switch tracks and control
volume from the steering wheel and make hands-free phone calls.
 
All those adapters have their place but for long term enjoyment, replace the
radio.
 
-bruce
bje@ripco.com
mike <ham789@netzero.net>: Sep 24 02:33AM -0700


>>> ESR.
 
>>> Greg
 
>> IIRC, you take the open circuit voltage and write it down.
 
You take a voltage reading under a known fixed load and write that down.
 
You plug those two voltage readings along with the load resistance
 
value into a formula (that I can't recall) and you get the internal
resistance of the battery.
Which voltage do you use?
When you apply the load, the voltage starts to drop.
So, which voltage along that curve do you use?
And when you "let go", the voltage won't return to the original level.
Note that the voltage at the instant you apply the load won't be available
unless you use a scope, or some otherwise accurate sampling to measure it.
 
Great in theory, but not nearly so simple in practice.
 
 
tabbypurr@gmail.com: Sep 23 10:42AM -0700

> SIL patterns invariably have one end with a square solder pad. This just helps you recognize which end is which when you turn your board over. I don't think it has a functional significance.
 
We never used that convention. They were either all square or all rounded.
 
 
NT
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Digest for sci.electronics.repair@googlegroups.com - 22 updates in 6 topics

"Dave M" <dgminala@mediacombb.net>: Sep 22 10:53AM -0500

Dave M wrote:
> D'Arsonval movements have about 20-30% range on the
> mechancial zero adjustment, so yours might be a long stretch for this
> method. Never know till you try!! Dave M
 
 
I forgot to mention that for the zener solution, you really need to select
as low power a zener that you can find, such as 400mW or lower.
The 1N4104 is a 10V, 250mW zener, with a test current of 1uA, and a max
current of 25ma, well within your requirements. In stock at Mouser.com.
 
Cheers,
Dave M
Jeff Liebermann <jeffl@cruzio.com>: Sep 22 10:22AM -0700

>It's what you do when you don't understand what you need, but you
>start building it anyway.
 
>If you need precision, you don't want an analog meter.
 
In college (about 1969), I build an "electronic slide rule" in the
form of an analog computer inside a brief case. Inside, it was two
log amps, a multiplier, range switch, and an anti-log amp. Input was
via two Bournes Helipot 10 turn pots (linearity 0.1%). Output was on
a mirrored scale analog panel meter about 6" in width. Accuracy was 3
decimal places in the lower part of the meter, and 2 decimal places
over the rest of the scale. However, I had to use temperature
compensation tables for the pots, multipliers, and amps to obtain that
level of accuracy.
 
What level of precision were you expecting?
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
"Ian Field" <gangprobing.alien1@virginmedia.com>: Sep 22 08:27PM +0100

"T i m" <news@spaced.me.uk> wrote in message
news:e898schb0qaru15b36kmcfvrroth86grt6@4ax.com...
>>kind of power supply.
 
> Because the reference voltage will be too close to the minimum voltage
> expected Ian?
 
The TL431 is actually a comparator with its own built in 2.5V reference.
 
In closed loop operation, that's as low as the cathode goes - you can
saturate it in open loop operation, but "Vce-sat" is around 2V.
whit3rd <whit3rd@gmail.com>: Sep 22 02:13PM -0700

On Thursday, September 21, 2017 at 10:51:33 AM UTC-7, T i m wrote:
 
> I was thinking of using either a voltage reference such as
> LM4040DIZ-10.0 or could I get away with a simple zener (BZX55C?) with
> associated resistor(s) please?
 
You can use any zener under 10V to do a 10V zero offset (just divide down the
input voltage until that 10V input matches the zener knee). So, with an
arbitrary zener (I'd use a TL431 as a 2.5V reference, they're convenient
and accurate) and a trimmer acting as voltage divider, it just remains
to make a range-setting resistor in series with the meter.
 
The important thing, is to doodle up a really nifty scale for your meter
that indicates 10V to 15V, with clear markings, along the pointer's arc,
maybe with a bunch of subdivision marks. Last time I did that, it took
a plotter and a bit of custom software to draw the arcs and labels,
then some fiddling with the faceplate of the meter to
affix it (warning: you need to worry about laser-print ink, paper, glue compatibility).
tabbypurr@gmail.com: Sep 22 03:38PM -0700

On Friday, 22 September 2017 05:05:35 UTC+1, Jeff Liebermann wrote:
 
> "The Windows programs for drawing analog meter scales"
> <http://www.tonnesoftware.com/meter.html>
> $35 for the full version.
 
fails to solve the issue AND adds pointless cost.
 
 
NT
tabbypurr@gmail.com: Sep 22 03:39PM -0700

On Friday, 22 September 2017 05:22:46 UTC+1, Foxs Mercantile wrote:
> > simple but time consuming producing a new dial paper
 
> With the low current Zener, it doesn't look like that will be
> necessary.
 
Oh, you've found a zener that's 10v +/- 1%?
 
 
NT
tabbypurr@gmail.com: Sep 22 03:45PM -0700

On Friday, 22 September 2017 05:42:36 UTC+1, mike wrote:
 
> >> End rant.
 
> > He's making a one off for use at home, not commissioning a new design of military hardware.
 
> The task is the same no matter who the customer.
 
Rubbish. For a large project all the specs have been calculated to meet the requirements, the contract gone through by a team of lawyers, and the task of the lec eng is to produce a circuit that meets all the given specs under all specified conditions.
 
For a one off at home the requirements are often not pinned down firmly, as in this case. There are no lawyers, no contract, and the elec eng's job is to trade off cost & complexity versus specs to find what turns out to be the most agreeable compromise for the client, oneself. In most cases this is a device that is much less tightly specced.
 
 
NT
tabbypurr@gmail.com: Sep 22 03:48PM -0700

On Friday, 22 September 2017 05:43:10 UTC+1, mike wrote:
> the precision measurement desired is never entered into
> any other system/program. The desired functionality
> could be obtained by a Sharpie mark or two on the face of the meter.
 
Indeed. This can be done in such a way to make it tidy. But the use of a zener means the scale will have to be calibrated, which is a waste of time, especially to get a nice neat result.
 
> It's what you do when you don't understand what you need, but you
> start building it anyway.
 
> If you need precision, you don't want an analog meter.
 
I see it's foolish claims day today.
 
 
NT
tabbypurr@gmail.com: Sep 22 03:57PM -0700

> On Thu, 21 Sep 2017 17:21:23 -0700, mike <ham789@netzero.net> wrote:
 
>Words like exactly, "as good as possible" have no place in a specification.
 
a common enough phrase for an in-house spec. Such phrases should be cleared up later of course, once the specifier knows what the engineers can actually do and what the options cost.
 
 
> >Specs are numbers and test methods. Specs include allowable
> >variations due to initial component tolerances, component age,
> >temperature, vibration, misuse.
 
Some do. Some are 'how can you get it as cheap as possible and still have it sell & not destroy our repuation.' Some are 'we want to beat what's out there, how good could you get it?' Some are 'we want it to do this.' etc etc etc.
 
 
> readings interpreting and so ITRW, we are 'most likely' to not require
> much in the way of precision or we wouldn't be using those things in
> the first place. ;-)
 
1% is doable for some analogue meters. That's enough precision for a lot of tasks.
 
 
NT
amdx <nojunk@knology.net>: Sep 22 08:13PM -0500


> Had I known, the "meter man" at Kutztown would have had exactly what you want in the size you want it, new or used. He has hundreds. Now you have to wait until spring.
 
> Peter Wieck
> Melrose Park, PA
 
I don't know if you are asking for an expanded scale meter, were the
0V line is 10V and FS line is 15 volts, so the whole range is only 5
volts. That's what I gleaned.
First you need to put a series 60K ohm resistor to make the meter read
FS with 15V applied. (for accuracy you should subtract the resistance of
the meter from the 60K ohms)
Then you need to add a circuit shown in these sites.
 
> http://www.radcomms.net/Expanded_Scale_Voltmeter.html
 
http://www.thebackshed.com/windmill/articles/ExpandedScaleVoltMeter.asp
 
> http://www.zbasic.net/forum/about1423.html
 
This last one will probably need a 10K resistor tied from one OUT to
the other OUT. Just so there is enough current to make the regulators
work properly.
 
Here's a youtube, I didn't watch it all, but you might learn something.
 
> https://www.youtube.com/watch?v=-z_j4MclCTk
 
Mikek
bruce2bowser@gmail.com: Sep 23 12:03AM -0700

mike wrote:
> >> End rant.
 
> > He's making a one off for use at home, not commissioning a new design of military hardware.
 
> The task is the same no matter who the customer.
 
At least the extra option should be there.
Jeff Liebermann <jeffl@cruzio.com>: Sep 23 09:35AM -0700

>> $35 for the full version.
 
>fails to solve the issue AND adds pointless cost.
>NT
 
The consensus seems to be to use an expanded scale analog voltmeter.
If the OP is going to build such a thing, he needs a new scale on his
analog meter. That can be done with the free version of the software.
(I just checked and it will do an expanded scale).
 
I usually ignore one line pontifications, but I'm curious. Why does a
new meter scale fail to solve the issue? Ummm... what issue?
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann <jeffl@cruzio.com>: Sep 22 10:08AM -0700

On Fri, 22 Sep 2017 07:55:03 -0400, bitrex
 
>On 09/20/2017 08:56 PM, Jeff Liebermann wrote:
(...)
>> refuses to allow a firmware downgrade.
 
>Thanks for the detailed reply! You can really brick Apple keyboads
>during a firmware update whaaaaat?!
 
Firmware upgrade didn't brick the keyboard, but killed a few keys.
 
It's been a few years and the keyboards were recycled long ago. Before
the upgrade, both wireless keyboards worked normally. Afterwards, the
BT KBD would work, but several keys were dead. Different keys on each
keyboard. I trashed one on my Mac Mini, while a customer trashed
theirs on some other Mac. I vaguely recall the firmware version as
1.4, but that might be incorrect.
 
The problem was not the failed firmware upload, but rather that Apple
does not allow firmware downgrades or reloading the same version that
is installed. This is just plain stupid as I could have recovered the
keyboard if either were allowed. I tried to find my postings to the
Apple forum on the topic, but failed. The user replies were not very
useful.
 
The reason that I mentioned it is that you will find Apple Aluminum BT
wireless keyboards at thrift shops with a few defective keys. In many
cases, new in the box. Everyone seems to assume that it's a
mechanical or liquid problem with the keyboard mechanics. However, I
believe it to be failed firmware upgrade problems similar to what I
experienced.
 
Caveat Emptor.
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Look165 <look165@numericable.fr>: Sep 22 08:21PM +0200

Generally, these devices are IR comunicating.
 
 
This needs an IR receiver on the PC.
 
 
 
bitrex a écrit :
Jeff Liebermann <jeffl@cruzio.com>: Sep 23 09:30AM -0700

On Fri, 22 Sep 2017 20:21:41 +0200, Look165 <look165@numericable.fr>
wrote:
 
>Generally, these devices are IR comunicating.
>This needs an IR receiver on the PC.
 
Huh? IrDA has been essentially dead for at least 10 years. I haven't
seen a full size keyboard that uses IR for at least that long. Most
everything these days uses some form of wireless to communicate.
 
Well, not totally dead. It is still possible to buy an IR keyboard
today:
<http://www.dsi-keyboards.com/product-category/keyboards/wireless-keyboards/ir-infrared-keyboards/>
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Look165 <look165@numericable.fr>: Sep 23 06:35PM +0200

A question of cost efficiency and stock dumping.
 
IR is so simple to integrate.
 
...And it uses "big batteries" !
 
Jeff Liebermann a écrit :
micky <NONONOmisc07@bigfoot.com>: Sep 23 11:01AM -0400

I'm thinking of installing a Gromaudio device that, if your car radio
has a CD changer input jack, allows for USB input, AUX input from a
cellphone, and for another $50 Bluetooth use of the cellphone through
the car speakers and an add-on microphone (in addition to the first
$150).
 
The most important feature for me is the USB input.
 
Do any of you know anything good or bad about Grom audio? Do any of you
know a competitor you would recommend (instead?)?
 
For example, Crutchfield sells a similar device that is only $70 for
everything (except the microphone and I can't even figure out how to
plug a microphone in). But assuming a microphone would work, would you
assume the one that sells for $200 is better than the one that sells for
70?
 
 
I've read as many reviews as I can find, but I wanted your opinions, and
I wanted to let you know such things are available. I never heard of
them before 4 days ago.
 
Their webpages will tell you if your car factory radio is compatible.
They say they even retain the use of SWC, steering wheel controls.
 
There are one or two other companies that sell devices that have
everything but the USB input, and I found something on ebay that had
everything and was only $18. At that price it's worth trying it just in
case it works, but based on the pictures, I don't think I could find one
that fit my particular jack. Hmm. Now it says "Only 4 available" and
the price has gone up to $20.
ss.chelsc@gmail.com: Sep 23 06:16AM -0700

SIL patterns invariably have one end with a square solder pad. This just helps you recognize which end is which when you turn your board over. I don't think it has a functional significance.
Foxs Mercantile <jdangus@att.net>: Sep 23 08:24AM -0500

> SIL patterns invariably have one end with a square solder pad.
 
The square pad is simply identification.
Pin-1, Cathode, (+) etc.
 
 
 
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
Jeff Liebermann <jeffl@cruzio.com>: Sep 22 09:54AM -0700


>Too much here to respond to,
 
Sorry. I was in a hurry and didn't have time to be brief.
Actually, I got interested in the topic and decided that it was worth
expounding in detail. Enjoy.
 
>but also consider that ePaper displays don't
>flicker. Even if you don't notice the flicker, moving your eyes creates
>distortion while the ePaper display is fixed.
 
Flicker doesn't bother me much, so I don't notice it. The usual
method of reducing LCD flicker is to use any vertical refresh rate
that's not 60 Hz. However, on my desktop (Samsung SyncMaster 243T
1920x1200), I'm running 60 Hz because higher refresh rates (72 and
75Hz) result in a blurred image. I can't really see it with graphics,
but with high contrast text, it's really obvious. I've also noticed
this on some other monitors but not on all monitors.
 
I don't know about eye movement causing distortion. The problem is
that on an LCD, each pixel is a combination of different color dots.
<https://www.google.com/search?q=lcd+magnified&tbm=isch>
To produce a white pixel, all the color dots need to be turned on
resulting in a large and potentially blurry pixel. That's not a
problem with e-paper, which only has to deal with turning one B&W dot
on and off.
<http://www.bit-101.com/blog/?p=2722>
Try a magnifier on your devices and see for yourself.
More on this (time permitting) if you're interested.
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
rickman <gnuarm@gmail.com>: Sep 22 04:19PM -0400

Jeff Liebermann wrote on 9/22/2017 12:54 PM:
> <http://www.bit-101.com/blog/?p=2722>
> Try a magnifier on your devices and see for yourself.
> More on this (time permitting) if you're interested.
 
Not sure what you mean when you say flicker doesn't bother you. You don't
have to see the flicker for it to cause a problem. The point is your eyes
don't adjust to a flickering screen as well as one that isn't flickering.
Your eyes constantly readjusting is what makes them tired.
 
--
 
Rick C
 
Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998
John-Del <ohger1s@gmail.com>: Sep 22 10:45AM -0700

On Wednesday, September 20, 2017 at 9:51:09 PM UTC-4, Ivan Vegvary wrote:
 
> Very little information on the web, what I would really like is a "DEFAULT RESET" function. I suppose I could put a switch in the battery circuit and do a manual shutoff.
> Thanks for any ideas.
 
> Ivan Vegvary, Oregon
 
 
 
$16.80 on ebay including shipping: item 172863952489
 
Unless you can try a firmware (available, possible?), you're looking at a $16.80 dead end...
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Digest for sci.electronics.repair@googlegroups.com - 25 updates in 5 topics

mike <ham789@netzero.net>: Sep 21 05:21PM -0700

On 9/21/2017 3:41 PM, T i m wrote:
 
>> This ain't rocket science folks.
 
> Maybe not but can appear as such to some (I think). ;-)
 
> Cheers, T i m
 
OK,
Let's go back to engineering 101.
What's the VERY MOST important part of a project?
It's the SPECIFICATION.
 
Exactly, precisely, concisely, unambiguously, completely stated
requirements.
This does NOT change. If you change your mind and change the spec,
you start a new project.
 
How do you know when you're done? You write acceptance criteria.
Exactly how the user, in this case you, is going to test the unit
to determine if you met the spec? If it passes the written acceptance
criteria, you succeeded. If it passes the test criteria, but doesn't
work, the specification was the problem. You get paid for this project
and start a new one with new specifications.
 
I can't emphasize how important the specification is. It's the number
one cause of project failure. You can't design for criteria that
were not specified.
It's easy to say, "I know what I'm designing for me...I don't need
no stinkin' specification." You'd be wrong. This thread is what you
get. Lots of rocket scientists when you really need a boat.
The very last place you want to discover that your forgot some
important requirement is when the completed device is deployed.
 
Words like exactly, "as good as possible" have no place in a specification.
 
Specs are numbers and test methods. Specs include allowable
variations due to initial component tolerances, component age,
temperature, vibration, misuse.
An example of misuse is, "what happens when the user hooks it
up backwards." I learned about vibration when I carried a
voltmeter on my motorcycle. When I needed it, it failed.
I took it apart and it poured out like sand.
 
The engineer doesn't need to know WHY you want what you want.
That's not his job. HOWEVER...if you state your objectives,
why you want to do this, you might find the bevy of rocket scientists
have a much better way to accomplish your objectives. I can't
count the number of times a user wanted an complicated gizmo,
but his objective could be achieved with a much different
and much simpler approach by repartitioning the system.
 
End rant.
 
First question I'd ask is, "are you gonna' stare at the meter 24/7?"
If not, get a cheap digital panel meter off EBAY, put a push button
in series and be done with it. If you're not battery
powered, you can probably tolerate the load and don't need the
push button.
 
But, back to your original request.
Take your current meter.
Put a series resistor to set the max voltage to 5V.
Put a 10V "battery" in series.
The remaining question is, "how do you implement the 10V
battery?"
Can your measured voltage ever get below 10V?
If so, your problem just got a LOT more complicated.
See "misuse" above.
 
If it were me, I'd use a 10V zener diode. If you can find
an affordable temperature compensated one that is accurate
over the range of current from zero to the max indication
on your meter and the ambient temperature range, do that.
Characterize the calibration.
Fire up your CAD program and make a new meter face.
Since you're making a new face, any stable zener voltage works.
Your meter is as accurate as your care in making the new face.
 
Are we having fun yet?
tabbypurr@gmail.com: Sep 21 08:10PM -0700

On Friday, 22 September 2017 00:23:14 UTC+1, T i m wrote:
 
> Ok.
 
> >I don't know which suits you better.
 
> Whatever works best on the day. ;-)
 
Both work fine. Which is easier.
 
> >> was ramping from 0 to 15V (and that's fine for a 12V lead acid).
 
> >If you had a perfect-knee perfectly accurate voltage zener then sure, but where will you find one of those?
 
> Pass, hence the questions.
 
http://www.datasheetcatalog.com/datasheets_pdf/B/Z/X/5/BZX55C10.shtml
shows that the breakdown voltage is below nominal at 0-250uA, and resistance far higher than at 5mA specified.
With Ir 0.1uA @ 7.5v you could use one, but you'd need to accept a yet unknown amount of nonlinearity in the scale. Far easier to just design something more accurate.
 
 
> Ok, but you still need to hold the -Ve end of the meter *at* 10V as
> the source goes between 10 and 15V? A LM4040DIZ-10.0 works like a
> zener so that would probably do.
 
The meter can just go on the opamp output, the offbiasing can be done on the input side.
 
> 15V. We would also have 20500 ohms (20k series resistor and 500 ohms
> of the meter) in parallel with the chip feed to help ensure it stays
> over 100uA.
 
or don't use it.
 
> functionality) is a very small series fuse and reverse biased diode
> across the input to the meter circuit ?
 
> Cheers, T i m
 
Enough resistance on the opamp input buys a lot of protection, a reverse diode across it buys more. Power line diode gets you more. You could add diodes to avoid one power section discharging while the other stays up.
 
Re running the meter off the voltage it's measuring, you could avoid some issues by having a 2nd opamp section pump up its supply rail voltage. Ultimate rail accuracy isn't required, the one opamp could work as both oscillator & rail voltage comparator.
 
Or easier, just cut Vin in half and run the opamp off the 12v battery.
 
 
NT
tabbypurr@gmail.com: Sep 21 08:13PM -0700

On Friday, 22 September 2017 01:22:14 UTC+1, mike wrote:
 
> but his objective could be achieved with a much different
> and much simpler approach by repartitioning the system.
 
> End rant.
 
He's making a one off for use at home, not commissioning a new design of military hardware.
 
 
> First question I'd ask is, "are you gonna' stare at the meter 24/7?"
> If not, get a cheap digital panel meter off EBAY, put a push button
> in series and be done with it.
 
not compliant with the spec
 
 
NT
Foxs Mercantile <jdangus@att.net>: Sep 21 10:26PM -0500

On 9/21/2017 6:35 PM, T i m wrote:
> But still, ohms law applies and with just a series resistor to limit
> the current for FSD, zero on the meter (re-marked to display 10V)
> won't reflect the required 10V.
 
Now, ya see, I missed that.
you want a 10-15 volt meter, not a 0-15 volt meter.
 
The simplest is a 20K resistor in series with a 10v zener diode.
Use a low current Zener so the knee works right at low values.
Something like this:
<http://www.mouser.com/ds/2/395/BZX55C2V0%20SERIES_D1610-1099630.pdf>
 
Depending on how non-linear the low end is, you can print a custom
dial scale that has been corrected for "this voltage is this mark."
<http://www.tonnesoftware.com/meter.html>
Although this one looks to be linear down to 10 uA or better.
10 uA would be approximately 0.2 volts above the Zener voltage.
or 10.2 volts on a 10-15 volt scale.
 
 
 
 
 
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
tabbypurr@gmail.com: Sep 21 08:59PM -0700

On Friday, 22 September 2017 04:26:17 UTC+1, Foxs Mercantile wrote:
> Although this one looks to be linear down to 10 uA or better.
> 10 uA would be approximately 0.2 volts above the Zener voltage.
> or 10.2 volts on a 10-15 volt scale.
 
simple but time consuming producing a new dial paper
 
 
NT
Jeff Liebermann <jeffl@cruzio.com>: Sep 21 09:05PM -0700


>simple but time consuming producing a new dial paper
>NT
 
"The Windows programs for drawing analog meter scales"
<http://www.tonnesoftware.com/meter.html>
$35 for the full version.
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Foxs Mercantile <jdangus@att.net>: Sep 21 11:22PM -0500

> simple but time consuming producing a new dial paper
 
With the low current Zener, it doesn't look like that will be
necessary.
 
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
mike <ham789@netzero.net>: Sep 21 09:41PM -0700


>> End rant.
 
> He's making a one off for use at home, not commissioning a new design of military hardware.
 
The task is the same no matter who the customer.
The more steps you skip, the more problems you have.
The more you think like a project manager, the better
managed your home projects.
Once you acquire the habit, you'll find that it adds
little to the time in the beginning and greatly simplifies
the end.
And it wastes far less time for rocket scientists in residence.
mike <ham789@netzero.net>: Sep 21 09:42PM -0700

On 9/21/2017 9:05 PM, Jeff Liebermann wrote:
 
> "The Windows programs for drawing analog meter scales"
> <http://www.tonnesoftware.com/meter.html>
> $35 for the full version.
 
I haven't seen the system requirements, but I'd wager that
the precision measurement desired is never entered into
any other system/program. The desired functionality
could be obtained by a Sharpie mark or two on the face of the meter.
 
One of the difficult engineering skills to acquire is the ability
to match the solution to the actual problem. Overkill is rampant.
It's what you do when you don't understand what you need, but you
start building it anyway.
 
If you need precision, you don't want an analog meter.
Foxs Mercantile <jdangus@att.net>: Sep 21 11:56PM -0500

On 9/21/2017 11:42 PM, mike wrote:
> It's what you do when you don't understand what you need, but you
> start building it anyway.
 
> If you need precision, you don't want an analog meter.
 
The meter program is capable of 100 "placed" I.e. non-linear tick
marks over the scale.
Much like some of the expensive lab grade equipment built with hand
lettered scales.
 
I am reminded of a story in Model Railroader back in the early '50s.
One of their staff members was in South Korea during the Korean war.
He was bound and determined to build himself a small table railroad.
He'd spent several weeks making sure every measurement was right and
the corners were square.
 
Finally, the big day arrived. He placed it in the corner of the
living room. Much to his horror, he had a triangular gap along one
side.
 
He asked his Korean attache how could he have possible had that
happen. The answer was simple, "Korean house not always square."
 
"But, your furniture and tables fit perfectly!"
 
"Korean tables and furniture not always square either."
 
 
 
--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com
T i m <news@spaced.me.uk>: Sep 22 09:16AM +0100

On Thu, 21 Sep 2017 17:21:23 -0700, mike <ham789@netzero.net> wrote:
 
<snip read and well meaning stuff for brevity>
 
>Words like exactly, "as good as possible" have no place in a specification.
 
I guess that depends on your background, viewpoint and goals mike?
 
e.g. I knew what I wanted, had a rough idea how it could be done and
just thought I run it past the panel for some real world *design*
feedback (I'm very much a dabbling designer but long term builder /
support guy etc).
 
>Specs are numbers and test methods. Specs include allowable
>variations due to initial component tolerances, component age,
>temperature, vibration, misuse.
 
Understood. I felt I laid out the relevant spec on my initial post, or
at least as far as someone who understood humans were concerned. ;-)
 
"Not a 'repair' question as such but I was thinking of using an old
skool 250uA FSD moving coil panel meter to read the 10 to 15V DC range
(a lead acid battery charge / discharge indicator), next to a 0-30A
Ammeter (inc shunt etc).
 
I was thinking of using either a voltage reference such as
LM4040DIZ-10.0 or could I get away with a simple zener (BZX55C?) with
associated resistor(s) please?"
 
So that was the need, the specs as far as I knew them and a potential
solution to help people 'get' what I was considering. What I didn't do
was signpost the fact that I was actually using a 0-5V panel meter to
display the 10-15V range. ;-(
 
The 'human' bit: A small (key fact) analogue (key fact) panel meter
connected to a lead acid battery (key fact) needs reading and those
readings interpreting and so ITRW, we are 'most likely' to not require
much in the way of precision or we wouldn't be using those things in
the first place. ;-)
 
So, what I was hoping I was saying is 'Could someone confirm or
recommend that 'for the (reading_between_the_lines) reasonably 'soft'
requirements, what is likely to offer *a* (there may be many equally
competent) real word / human solution?
 
So, anyone who knows their stuff and who understands people *might*
have already answered the question on 'how much money', 'how much
effort', 'how complex / simple' would any solution likely to be in
their heads. <shrug>
 
>An example of misuse is, "what happens when the user hooks it
>up backwards."
 
Understood, but unbeknown to anyone here, that will all be catered for
*in my case* by the use of polarised connectors that could never end
up reverse connected elsewhere.
 
>I learned about vibration when I carried a
>voltmeter on my motorcycle. When I needed it, it failed.
>I took it apart and it poured out like sand.
 
Again, understood. In this instance the only clue I gave to the
potential size of the battery was the scale of the ammeter (0-30A) and
that scale was because it is to be used on an electric outboard motor
that has a maximum current of 30A and will in fact be running from 3 x
31Ah batteries joined in parallel. Because it's in a boat the panel
meters will have a very comfortable ride. ;-)
 
>The engineer doesn't need to know WHY you want what you want.
 
Quite. ;-)
 
>That's not his job. HOWEVER...if you state your objectives,
>why you want to do this, you might find the bevy of rocket scientists
>have a much better way to accomplish your objectives.
 
Again, how would knowing what I wanted to use it for, more than I
already specified help anyone actually resolve the question asked? I'm
not saying they couldn't then rule out or add 'other things' but
nothing offered so far has affected the physical outcome of this
particular project in a physical sense.
 
That said, I could have been using a large and expensive panel meter,
graduated in .2v increments, rather than one only marked in whole volt
increments <g>. But the reading of the meter is my problem, making it
read 10-15V is the bit I needed help on (please). ;-)
 
As an aside here ... I ran a Telephone Help Desk for over 5 years and
feel I became fairly good at 'gauging' people. If their opening gambit
was 'Your beige box isn't working' I knew to deal with them at a
different level (initially at least) compared with someone who said
'Our X.25 PAD No3 doesn't seem to be bringing up a Link LED?'.
 
Just the same as the PC user reporting that their 'screen is blank'
when it in fact has a flashing cursor in the top left corner. It's not
what they expected or wanted but it's far from 'blank'. ;-)
 
>count the number of times a user wanted an complicated gizmo,
>but his objective could be achieved with a much different
>and much simpler approach by repartitioning the system.
 
Oh, absolutely and you / anyone (who hasn't already dealt with me on
here) wouldn't have any idea what I do or do not know and may have
already considered. My solution potentially required 2 components
(resistor and zener) so it couldn't get much simpler so it's just a
matter of selecting the 'best' (all things considered) types of those
components, if they are appropriate.
 
>End rant.
 
Points noted and generally agreed mike. ;-)
 
>First question I'd ask is, "are you gonna' stare at the meter 24/7?"
 
No, it's something I'll glance at either now and again or specifically
when I change something and need to see the consequences (like
changing 'speed' on my electric outboard.
 
>If not, get a cheap digital panel meter off EBAY,
 
Already Done.
 
>put a push button
>in series and be done with it.
 
No need mike. It will likely only be in circuit when required
(testing) and the current drawn when it is will be insignificant
relative to the other loads and battery capacity (93Ah).
 
> If you're not battery
>powered, you can probably tolerate the load and don't need the
>push button.
 
Check.
 
>But, back to your original request.
 
Cool. ;-)
 
>Take your current meter.
 
Check.
 
>Put a series resistor to set the max voltage to 5V.
 
Check (~20k?)
 
>Put a 10V "battery" in series.
 
Bench PSU + DMM, check.
 
>The remaining question is, "how do you implement the 10V
>battery?"
 
Check.
 
>Can your measured voltage ever get below 10V?
 
Hopefully not. It will only ever be 10.5V or higher or 14.4V or lower
... or disconnected completely (points already considered etc).
 
>If so, your problem just got a LOT more complicated.
>See "misuse" above.
 
Quite. ;-)
>an affordable temperature compensated one that is accurate
>over the range of current from zero to the max indication
>on your meter and the ambient temperature range, do that.
 
Check. I did suggested a BZX55C in my OP but not being a designer I
would have no real idea where to start re finding the 'right'
component (by that I mean there is probably a 'go-to' device that
'most people' would typically use under these circumstances, like they
might a 7805 or 555) ;-)
 
>Characterize the calibration.
 
Ok?
 
>Fire up your CAD program and make a new meter face.
 
Unlikely (see all the above). ;-)
 
>Since you're making a new face, any stable zener voltage works.
 
Chances are I'm not so ...
 
>Your meter is as accurate as your care in making the new face.
 
Quite ... and with simple 1V increments over a 10-15V range should
give me a better 'feel' of the voltage than trying to read a similarly
sized meter graduated in .2v increments in the 0-15V range all whilst
going along a river in a small folding boat. ;-)
 
>Are we having fun yet?
 
Very much so, thanks mike. ;-)
 
Cheers, T i m
T i m <news@spaced.me.uk>: Sep 22 09:29AM +0100


>>> End rant.
 
>> He's making a one off for use at home, not commissioning a new design of military hardware.
 
>The task is the same no matter who the customer.
 
It can and maybe should be, in an ideal world. I say that because I
hate having to deal with 'fools who rush in' or those expecting me to
make technical / choice decisions on their behalf (like getting them
some 'size 10, brown, lace up leather shoes'). ;-(
 
>The more steps you skip, the more problems you have.
 
'May have'.
 
>The more you think like a project manager, the better
>managed your home projects.
 
Agreed. I like to understand as much about something as I can.
However, my ability to do so, time available to do so and the
pertinence of doing so don't always allow me to do so or to do so to
the level I would like. Sometimes you just have to get stuck in. ;-)

>Once you acquire the habit, you'll find that it adds
>little to the time in the beginning and greatly simplifies
>the end.
 
Agreed 100%.
 
>And it wastes far less time for rocket scientists in residence.
 
Quite ... however, this is a 'discussion' group and so does have an
element of that, along with the hard science / fact stuff.
 
Part of the 'human' bit is not making a post (especially the initial
one) too long (I fail most of the time) as it will put people off
reading it and if there were any further points that need refining
they could be done with a simple Q&A.
 
e.g. I initially outlined the fairly close detail at a level relevant
to my needs and understanding (IMHO anyway). I didn't expand on what I
was going to actually use it for because it didn't really matter to
the question. I left it open to the reader to ask any supplementary
questions as they felt relevant. ;-)
 
Cheers, T i m
"Dave M" <dgminala@mediacombb.net>: Sep 22 10:41AM -0500

T i m wrote:
> the question. I left it open to the reader to ask any supplementary
> questions as they felt relevant. ;-)
 
> Cheers, T i m
 
Wow, what a long thread about such a simple problem. Here's a web page
describing exactly the circuit you need for an expanded scale voltmeter
(http://sound.whsites.net/articles/meters.htm). Scroll down to Apragraph
5.0 to get to the expanded voltmeter discussion. It uses a 1ma movement for
the discussion, so you'll have to calculate the resistor values to fit your
meter. It uses a 10V zener and one more resistor.
 
Another method that I've used in the past to make an expanded scale meter is
to suppress the mechanical zero. You still have (in your case) a 0-15V
meter, but the needle doesn't get up to the "0" mark until 10V is felt
across the circuit. After that, the meter responds normally, up to 15V full
scale. So,with this approach, you don't need any extra circuitry to make an
expanded scale meter.
This means that you'll have to open the meter and (CAREFULLY!!) move the
mechanical zero tang. First, apply 10V to the circuit. Then, turn the
mechanical zero tang so that the pointer goes down to the "0" mark.
Reassemble the meter movement, and you're all done.
 
To make this approach work, your meter movement must have enough mechanical
adjustment range to suppress the pointer enough so that it needs 10V across
the circuit to make the meter read "0" V. Typically, D'Arsonval movements
have about 20-30% range on the mechancial zero adjustment, so yours might be
a long stretch for this method. Never know till you try!!
Dave M
Phil Allison <pallison49@gmail.com>: Sep 21 04:55PM -0700

GS wrote:
 
--------------------
 
> > Test ESR or correlate it with open cct cell voltage?
 
> ESR.
 
** Err - with an ESR meter, like this one:
 
http://bobparker.net.au/esr_meter/esrmeter.htm
 
 
 
..... Phil
mike <ham789@netzero.net>: Sep 21 09:49PM -0700

On 9/21/2017 4:55 PM, Phil Allison wrote:
 
> http://bobparker.net.au/esr_meter/esrmeter.htm
 
> ..... Phil
 
Have you ever tried to measure the ESR of a battery with one of
these?
 
I bought an EBAY RLC/ESR tester.
Found it useless measuring batteries.
NO, putting a cap in series didn't help.
Tried testing two batteries in series(reversed
so the terminal voltage was zero).
Not sure why, but I couldn't find any way to test battery ESR
with it. Had to go back to pulse generator and scope.
Phil Allison <pallison49@gmail.com>: Sep 21 10:05PM -0700

mike wrote:
 
---------------
 
> > http://bobparker.net.au/esr_meter/esrmeter.htm
 
> Have you ever tried to measure the ESR of a battery with one of
> these?
 
** Been doing just that for 20 years, I know Bob Parker and he endorses the method.
 
I wrote a short article on the idea and won nice prize from the publishers.
 
Long as the ESR meter uses high frequency AC ( 20kHz to 100kHz) to measure impedance it will do cells as well.
 
 
 
.... Phil
ggherold@gmail.com: Sep 22 06:06AM -0700

On Thursday, September 21, 2017 at 7:46:39 AM UTC-4, John-Del wrote:
 
> > Greg
 
> IIRC, you take the open circuit voltage and write it down. You take a voltage reading under a known fixed load and write that down. You plug those two voltage readings along with the load resistance value into a formula (that I can't recall) and you get the internal resistance of the battery.
 
> Waaaay too much trouble IMO. In recent years, I've found OC voltage sufficient to determine battery condition of basic alkaline cells. For high drain applications such as flash lights, anything at 1.5 is fine. For lower drain things like pocket radios or remote controls, anything above 1.3 works for many months. Any cell that reads 1.55 or above is virtually new.
 
Wow, too much trouble? It's just ohm's law.
Say V_O is open circuit voltage, V_L is with load R.
I = V_L/R
Bat_R = (V_O-V_L)/I
(The ESR may change with load current...
I don't know.)
 
George H.
John-Del <ohger1s@gmail.com>: Sep 22 06:51AM -0700

> (The ESR may change with load current...
> I don't know.)
 
> George H.
 
Yes, waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay too much trouble. With alkalines, a volt meter tells me *immediately* what I need to know if I don't have my battery checker with me. If it's 1.6, it's new. 1.5 good as new. Anything above 1.3 is good for at least half the life of a new battery. Anything lower I don't bother with.
 
In the old days, some batteries would read decent OC voltage and still sag under their intended load. I haven't seen a battery in many years that would show good OC voltage and sag under load.
bitrex <bitrex@de.lete.earthlink.net>: Sep 22 07:55AM -0400

On 09/20/2017 08:56 PM, Jeff Liebermann wrote:
> you try to recover by installing an earlier version, Apple's installer
> refuses to allow a firmware downgrade.
 
> Have fun keyboard shopping.
 
Thanks for the detailed reply! You can really brick Apple keyboads
during a firmware update whaaaaat?!
bitrex <bitrex@de.lete.earthlink.net>: Sep 22 07:56AM -0400

On 09/21/2017 07:19 AM, whit3rd wrote:
> or mice to pair with? Connection isn't just automatic, you have to AUTHORIZE the
> bluetooth item from the host computer.
 
> Either System Preferences/Bluetooth or the Bluetooth pulldown menu is a place to start.
 
Thanks for the reply, it's just frustrating that I have to use a _wired_
keyboard and mouse to get a wireless set to work. I don't have any wired
keyboards or mice lying around! What is this, 2002?
jack4747@gmail.com: Sep 22 05:05AM -0700

Il giorno giovedì 21 settembre 2017 13:19:20 UTC+2, whit3rd ha scritto:
> or mice to pair with? Connection isn't just automatic, you have to AUTHORIZE the
> bluetooth item from the host computer.
 
> Either System Preferences/Bluetooth or the Bluetooth pulldown menu is a place to start.
 
If I remember correctly when a Mac starts, if there is no input device conneted (keyboard or mice), it turns on automatically the BT and starts the BT assistant to connect a BT keyboard or mice.
 
Bye Jack
Jeff Liebermann <jeffl@cruzio.com>: Sep 16 08:47PM -0700


>How do you tell when the bar lube is blocked?
 
Remove the bar and chain. Chain oil comes out of a hole that mates
with a corresponding hole in the bar that only goes half way through
the bar (i.e. the hole is only on one side of the bar). Run the saw
without the bar, chain, or cover, for about 60 seconds. You should
see oil slowly dripping or exiting as a small mist out of the hole in
the body. If nothing comes out, it's clogged further upstream or the
pump is trashed. Lots of YouTube videos on testing and fixing
chainsaw oilers:
<https://www.youtube.com/results?search_query=chainsaw+oiler>
 
More common is that the oil hole in the bar is clogged with a mixture
of oil, dirt, and sawdust. This would probably be a good time to
clean out the bar groove, dress the bar, remove the sharp edges,
flatten any dings, lube the sprocket, etc.
<https://www.google.com/search?q=chainsaw+bar+maintenance>
No need for the specialized tools. Just a scraper that fits in the
groove, hand file, and trisquare. If the lack of oil has caused the
bottom of the side plates on the chain to wear and the edges of the
bar to mushroom into sharp edges, you may need to have the bar squared
and the groove deepened.
 
Also, it helps to flip over the bar to extend the wear life. Most
people don't like the way the saw looks with the manufacturers name
inverted on the bar, but that's a small price to pay for extending the
life of the bar.
 
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann <jeffl@cruzio.com>: Sep 17 10:05AM -0700

On Sun, 17 Sep 2017 09:53:14 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
 
>Meanwhile, there's Sci-Hub:
><https://scihub.org>
 
Ooops. Wrong URL for Sci-Hub. This should be the right one.
<https://sci-hub.io>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
rickman <gnuarm@gmail.com>: Sep 22 04:26AM -0400

Jeff Liebermann wrote on 9/21/2017 10:53 PM:
> library in my pocket. As more of what I have on my bookshelf becomes
> available in electronic format, more of my paper books will become
> donated or recycled.
 
Too much here to respond to, but also consider that ePaper displays don't
flicker. Even if you don't notice the flicker, moving your eyes creates
distortion while the ePaper display is fixed.
 
--
 
Rick C
 
Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998
rickman <gnuarm@gmail.com>: Sep 16 08:58PM -0400

~misfit~ wrote on 9/16/2017 8:49 PM:
> seats' in the search parameters. I'll go back to my policy of not clicking
> obfuscated URLs - which for some odd reason I didn't think would be needed
> here.)
 
Not sure what you are reading. Traffic laws are state issues in the US
although there is a certain amount of "coordination" by the Federal
government. I don't know of any states which doesn't require seat belts to
be worn by everyone in a vehicle. I'm not familiar with *all* of the 50
states. What did you find that says otherwise?
 
--
 
Rick C
 
Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998
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